Fluid pump



y 1958 I L. c. BULLINGTON 2,833,217

FLUID PUMP Filed Sept. 8, 1953 2 Sheets-Sheet 1 LEO C. BULLINGTON, INVENTOR.

HUEBNER, BEEHLER,

WORREL 8 HERZIG.

ATTORNEYS.

FLUID PUMP Leo C. Bullington, Montebello, Calif. Application September8, 1953, Serial No. 378,774 4 Claims. (Cl. 103-37 This invention relatesto fluid pumps; and more particularly to fluid pumps wherein the outputvolume of the pump is automatically adjusted in accordance with the;output pressure against which the pump must force the fluid, so that asthe output pressure increases, the volume decreases, thereby maintainingrelatively constant load on the motive means driving the pump.

It is an object of this invention to provide an improved pump in whichthe output volume of the pump varies automatically and inversely withthe output pressure against which the fluid must be forced by the pump.

It is a further object of this invention to provide a fluid pump havingautomatic means for continuously and variably adjusting the volumetricdisplacement of the pump inversely with the fluid pressure against whichthe pump must force the fluid.

In accordance with these and other objects which will become apparenthereinafter, a preferred embodiment of the instant invention will now bedescribed with reference to the accompanying drawings wherein:

Fig. l is a longitudinal elevational section of the Fig. 2 is across-section taken on line 22 in Fig. 1;

Fig. '3 is a cross-section taken on line 3-3 in Fig. 1; and

Fig. 4 is a cross-section taken on line 4--4in Fig. 1.

Referring to the drawings, 11 designates. a housing having .a pair ofcylindrical cavities. or cylinders 12 and 13 formed therein. A pair ofshafts 14 and 16 are rotatably mounted in the housing 11. The shaft 14is mounted by a pair of aligned bearings 17 and 18, and the shaft 16 ismounted by a pair of aligned bearings 19 and 21. ,In the'particularembodiment shown, the shafts 14 and 16 are aligned.

Each of the shafts .14 and 16 is disposed generally transverse to itsrespective cylinder 12, 13, and includes a crank portion aligned withthe respective cylinder. The shaft 14 is provided with a crank 22 whichrotates in the left portion of the housing 11, in the crank chamber 23associated and communicating with the cylinder 12; and the shaft 16includes a crank 24,-rotating in the nitedStatcs Patent "ice municationwith either the cylinder 12 or 13, or the passageway 32.

Resilient linking means torsionally linking the shafts 14 and 16 isprovided, and such means will now be de scribed.

The shaft 14 extends beyond the crank chamber 23, outside and past thebearing 18, and to the shaft is secured a housing 41, by means of bolts42. The shaft 16 also projects beyond its crank chamber 26 and past itsbearing 19 into the housing 41, and is journalled in the housing 41 bybearings 43 and 44. The shaft 16 is resiliently, torsionally linked tothe shaft 14 by means of a torsion spring 46 encircling the shaft 16.One end of the spring 46 is anchored to the shaft 16 at 47, while theother end is anchored to the housing 41, and hence to the shaft 14, atthe spring end 48.

The pump of the present invention may be driven from either endthat is,either the shaft 14 or the shaft 16 may be driven; but both shaftsshould not be driven simultaneously. If the shaft 14 is to be driven, itshould be rotated in the direction shown by the arrow 49, while if theshaft 16 is to be driven, it should be rotated in the direction shown bythe arrow 51. Assuming the shaft 14 to be driven in the direction shownby the arrow 49, it will be seen that torque is transmitted from theshaft 14 to the shaft 16 through the spring 46. By virtue of theresilient link between the two shafts, in the form of the spring 46, thephase displacement between the two shafts will be directly proportionalto the torque transmitted from the shaft 14 to the shaft 16. The

torque transmitted will in turn be dependent upon the resistance torqueencountered by the crank 24, and this in turn will vary with the fluidpressure against which the piston 28 must force the fluid out the outletpipe 38.

The linking means between the shafts 14 and 16 also includes a dashpotmeans, including the housing 41, which is effective to dampen rapidchange in phase relation between the two shafts 14 and 16. Descriptionof this dashpot means will be deferred until the basic operation of thepump has been briefly explained,

below.

crank chamber 26 associated and communicating with the cylinder 13.Within the cylinders 12 and 13 reciprocate, respectively, pistons 27 and28, which are connected to their respective cranks 22 and 24 by pistonrods 29 and 31, respectively. v I

A passageway 'or fluid conduit means 32 connects jthe upper portion ofthe two cylinders 12 and 13. Inlet conduit means to the cylinders 12 and13: is provided inthe form of a pair of pipes 33 and 34 feeding into therespective cylinders 12 and 13, and including inletcheck- I vcylinder13, and vice versa.

up as the piston 29 is coming down.

With the pump at rest, the two cranks 22 and 24 are substantiallyaligned, that is, the pistons 27 and 28 are substantially in phase witheach other. Under these conditions, when the shaft 14 is rotated, thetwo pistons 27 and 28 rise and fall together so that maximum fluid isdrawn in with each stroke through the valves 36 and 37, and maximumfluid is forced out throughthe valve 39 with each up stroke.- If theoutput pressure into which the outlet pipe 38 feeds is very low so as tobe negligible, then the back pressure on the pistons, in particular onthe piston 28, is very low, and hence the resistance torque on the crank24 and shaft 16 is low. Under these conditions there is very littletorque transmitted through the spring 46, and the phase displacementbetween the two shafts 14 and 16 is small. Thus We have a condition ofmaximum volumetric displacement of fluid with each revolution of thepump, and against minimum pressure.

Let it now be assumed that the shafts 14 and 16 are moved 180 apart, sothatthe' piston 28 is going In other words, the pistons are exactly 180out of phase. Under this circumstance there will be no fluid forced outthrough the outlet conduit 38, because all the fluid displaced by thepiston 27 will be immediately accepted by the Thus we see that thevolume output of the pump may be varied between a maximum, whentheshafts 14 and 16 are in phase, down to zero, when the shafts 14 and16 are l out ifdesired, and this may be placed anywherefin comof phase.In between, say at crank displacement,

3 the output volume will be'between maximum and zero.

It has been shown that with negligible output presu e at e qut t-ceduitfi the tw ha t 1 m 16 rotate substantially in phase, since thetorque transmitted through the, spring 46 is negligible. Now let it besupposed that the output pressure increases. In this event the backpressure encountered by the piston 28 increases, and a resistance torquewill be .aPPlied against theshaft 16 through the crank 24. This torqueforces the spring ,46 to wind up around the shaft 16 and creates aphase,displacement-between the shaft 14 and the shaft 16, the latter nowlagging in phase behindthe shaft .14. Under .this circumstance thevolume of fluid ,put out through the outlet 38 decreases, since aportion of the fluid put out from the cylinder 12 is taken up in thecylinder 13 and vice versa, and only the remainder goes out through. theoutlet 38. This decreased volume output permitsof a greater pressure tobe delivered by the pump for a given energy input of the driving means,since pressure times volumetric output is proportional to the powerinput. Therefore, it will be seen that if constant power input isapplied, the output pressure will go up as the volume output goes down.

Thus is will be seen that as the output pressure into which the pumpmust feed the fluid goes up, the volume or flow rate correspondinglydecreases, thus keeping constant power load at all times on the primemover driving the shaft 14. The prime mover is thus able at all times todeliver constant horse power to the pump, with the pump automaticallyadjusting itself to absorb all of the horse power put out by the primemover, either in terms ofhigh volume .and low pressure, or low volumeand high pressure, or any intermediate range.

When there is a relative phase displacement between the two shafts 14and 16, as for example, when the shafts are 90 displaced, and the pumpis pumping medium volume at mediumpressure, the resistance torqueapplied against the crank 24 through the piston 28 varies considerablyover one revolution of the shaft 16. Such variation would cause aconstant shifting in phase between the shaft 16 and the shaft 14throughout .one cycle or revolution, were it not for the dashpot meansmentioned hereinbefore and contained within. the housing .41.

Thismeans is shown in Figs. 1 and 4, wherein the housing 41 is shown ashaving two cylindrical cavities or dashpot cylinders 52 and 53. In'thesecylinders reciprocate, respectively, pistons 54 and 56 connected,respectively, by rods 57 and 58 to acrank 59 formed on the end of theshaft .16 between .the bearings .44 and 43. The two cylinders 52 and 53are connected at their upper regions orheads by a passageway 61, whichcommunicates with the cylinder 52 through a restricted orifice 62 andwith the cylinder 53through arestricted orifice 63. The passageway 61and thecylinders 2 and 53, above the heads of their respective pistons,are filled with a fluid, preferably a liquid, such as hydraulic oil.This oilserves as a .damping means for limiting the speed of phasedisplacement between the shaft 14, secured to the housing 41, and theshaft.16, linked to the pistons 54 and 56, respectively,

It will be seen thatrelative phase displacementbetween the shafts 14 and16 causes piston 54to advance or go up in its cylinder 52, while piston'66 is retract-- and 16, in spite of the widely varying torqueresistance encountered by the crank 24 on the shaft 16. As a result, forany given condition of operatiouthat is, for any given output pressureat the outlet pipe 38, the phase displacement between the shafts 14 and16 will settle upon a predetermined angular displacement, which is afunction of the average torque transmitted from the shaft 14 to theshaft 16, rather than the rapidly fluctuating instantaneous torque whichoccurs throughout any given revolution.

In practice, it is preferred to space the orifices 62 and/or 63 atpoints somewhat short of the maximum excursions of their respectivepistons 54'and 56, as shown in Figs. 1 and 4. In this way, positivestops are provided for the pistons 54 and 56, since when the pistonshave passed the orifices 62 and 63, respectively, no further fluidcanescape, and the pistons are brought to an absolute halt. Thisprovision limits the relative phase displacement between the shafts ,14and 16, which instead of being able to shift from zero to 180 relativephase displacement, will now be limited to a range of from 10 to 170,for example.

The principles of the instant invention also have special application inthe field of hydraulic transmissions. For such a use, one of the shafts,for example the shaft 14, serves ;.as a-drive shaft coming from a primemover. Theshaft 16 is cut off at the bearing 21, and an output shaft issecured to the housing 11 which is now allowed to rotate freely. Theoutput shaft is aligned with the shaft 14, .,By providing specialvalving means at the outlet in place of the valve 39, a transmission isreadily provided which automatically adapts its coupling ratiototheiresistance torque encountered by the output shaft, so that maximumhorse power from the prime mover is employed'at all times.

While theinstant invention has been shown and described herein ,in whatis conceived to be the most practical and preferred embodiment, it isrecognized that departures may be .made therefrom within the scope ofthe'invention, which is therefore not to be limited to the detailsdisclosed herein but is to be accorded the full scope. of the claims.

What isgclaimed is:

l. Mechanism employing fluid and comprising: a housing having a pair ofcylinders therein; a pair of shafts rotatably mounted in said housing,each shaft having a crank therein; a pair of pistons reciprocable,respectively, insaid cylinders; a pair of piston rods connecting saidpistons, respectively, to the respective cranks; resilient linking meanstorsionally linking said shafts so ,;that one shaft may drive the other;said linking means -including dashpot means effective to dampen rapidphase displacements between said shafts; said dash pot means comprisinga housing secured to one 'ofsaid shafts and having a dashpot cylindertherein, a dashpot crank formed on the other of said shafts, adashpot-piston -reciproeable in said dashpot cylinder, a dashpo tpiston-rodconnected between said dashpot piston and dashpot crank, andrestricted conduit means communicating with said dashpot cylinder; fluidconduit 7 means connecting said cylinders; inlet conduit means to saidcylinders including check valve-means; and outlet conduit means fromsaid cylinders including check valve means. i

2. Mechanism employing fluid and comprising: a housing having a pair ofcylinders therein; a pair of shafts rotatably mounted in said housing,each shaft having a crank therein; a pair of pistons reciprocable,respectively, in said cylinders; a pair of piston rods connecting saidpistons, respectively, to the respective cranks; resilient linking meanstorsionally linking said shafts so that one may drive. theother; saidlinking means including dashpot means effective to dampen rapid phasedisplacements between said shafts; said dashpot means comprising adashpct housing secured to one of said shafts and having a pair ofcylinders therein, dashpot crank means disposed in said dashpot housingand secured to the other of said shafts, a pair of dashpot pistonsreciprocable, respectively, in said dashpot cylinders and connected tosaid dashpot crank means, conduit means communicating between saiddashpot cylinders and liquid filling said conduit means and dashpotcylinders in front of said dashpot pistons; fluid conduit meansconnecting said cylinders; inlet conduit means to said cylindersincluding check valve means; and outlet conduit means from saidcylinders including check valve means.

3. Mechanism employing fluid and comprising: a housing having a pair ofcylinders therein; a pair of shafts rotatably mounted in said housing;each shaft having a crank therein; a pair of pistons reciprocable,respectively, in said cylinders; a pair of piston rods connecting saidpistons, respectively, to the respective cranks; resilient linking meanstorsionally linking said shafts so that one shaft may drive the other;said linking means including dashpot means eflective to dampen rapidphase displacements between said shafts; said dashpot means comprising adashpot housing secured to one of said shafts and having a pair ofcylinders therein, dashpot crank means disposed in said dashpot housingand secured to the other of said shafts, a pair of dashpot pistonsreciprocable, respectively, in said dashpot cylinders and connected tosaid dashpot crank means, conduit means communicating with therespective dashpot cylinders at points short of the maximum excursionsof said dashpot pistons from 6 said other shaft, and liquid filling saidconduit means and said dashpot cylinders in front of said dashpotpistons; fluid conduit means connecting said cylinders; inlet conduitmeans to said cylinders including check valve means; and outlet conduitmeans from said cylinders including check valve means.

4. Mechanism employing fluid and comprising a housing having a pair ofcylinders therein, a pair of aligned shafts rotatably mounted in saidhousing, each shaft having a crank therein, a pair of pistonsreciprocable, respectively, in said cylinders, a pair of piston rodsconnecting said pistons, respectively, to the respective cranks, atorsion spring disposed coaxi-ally of said shafts, means connecting oneend of said spring to one of said shafts, means connecting the other endof said spring to the other of said shafts, fluid conduit meansconnecting said cylinders, inlet conduit means to said cylindersincluding check valve means, and outlet conduit means from saidcylinders including check valve means.

References Cited in the file of this patent UNITED STATES PATENTS1,575,519 A-msler Mar. 2, 1926 2,172,103 Kotaki Sept. 5, 1939 2,327,787Heintz Aug. 24, 1943 FOREIGN PATENTS 269,747 Great Britain Apr. 28, 1927517,236 Germany Feb. 2, 1931 620,430 Great Britain Mar. 24, 1-949

